• Alex Savin
• March 31, 2022
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The Influence of Body Mass in Skiing

Body mass index is important for every person’s health, but it has an even bigger significance for an athlete’s quality. BMI can influence an athlete’s stamina and performance, BMI can affect an athlete’s endurance and performance, so there has been a lot of scientific research done on this topic. In this article, we will look at the scientific evidence that shows the effect of body weight in skiing.

Body Mass in Skiing

The body mass index (BMI), or Quetelet index, is a heuristic proxy for human body fat based on an individual’s weight and height. BMI does not measure the percentage of body fat. The Belgian polymath Adolphe Quetelet invented it between 1830 and 1850 while developing “social physics”. Body mass index is defined as the individual’s body weight divided by the square of their height. The formulae universally used in medicine produce a unit of measure of kg/m2. BMI can also be determined using a BMI chart, which displays BMI as a function of weight (horizontal axis) and height (vertical axis) using contour lines for different values of BMI or colors for different BMI categories.

Energy Cost Calculations

The influence of body weight on the performance in cross-country skiing has been studied by:

1. Dimensional analysis of the ratio (R) between the factors of importance to power production ([latin capital V with dot above]O2max, acceleration of gravity) and the braking powers, e.g., friction and air resistance.
2. Measuring the energy cost of level skiing (N = 6).
3. Comparing male world-class skiers (N= 5) with less successful ones (N = 34) and female winners of the National Championships (N = 9) with non-winners (N = 9) in regard to the relationship between body weight and [latin capital V with dot above]O2max, The dimensional analysis revealed that R was less than unity for rather steep uphills.

R was greater than unity for level, downhill, and less steep uphill skiing. Thus, light skiers will be favored on steep uphill slopes, whereas heavier skiers have advantages in the other parts of the track. Energy cost per kilogram for level skiing was inversely related to the transported mass. Per unit of distance, this cost was positively related to velocity. The world-class skiers displayed significantly greater [latin capital V with dot above]O2max than the less successful ones, regardless of the unit used. The lowest standard deviation among the world-class skiers was attained when expressing [latin capital V with dot above]O2max as ml-min-1 [middle dot] kg-2/3. The present results indicate that R will be quite close to unity, and therefore the performance capability would theoretically be independent of body mass for skiing. Furthermore, [latin capital V with dot above]O2max is preferably expressed as ml [middle dot] min-1 [middle dot] kg-2/3 for cross-country skiers.

Basal metabolic rate is scaled to body mass to the power of 0.73. We evaluated whether a similar scaling applies when the O2 transport capacity of the body is challenged during maximal exercise (i.e., at maximal O2 uptake, V˙O 2max). The allometric relationship between V˙O 2max and body mass (y=a • x b, where y is V˙O 2max and x is body mass) was developed for 967 athletes representing 25 different sports, up to 157 participants in each sport. With an increasing number of observations, the exponent approached 0.73, while for ventilation, the exponent was only 0.55. By using the 0.73 exponents for V˙O 2max, the highest value [mean (SD)] for the males was obtained for the runners and cyclists [234 (16) ml • kg−0.73 • min−1], and for the females, the highest value was found for the runners [189 (14) ml • kg−0.73 • min−1]. For the females, aerobic power was about 80% of the value achieved by the males. Scaling may help both understand variation in aerobic power and define the physiological limitations of work capacity.

In addition to fat-free mass, hormonal status, genetics, and energy balance, previous physical activity has influenced energy turnover during resting (RMR = resting metabolic rate) or basal conditions(BMR = basal metabolic rate). This article presents data on BMR from elite endurance athletes (4 female and 4 male), at least 39 h after their last training session, compared with sedentary nonathletic controls matched for sex and fat-free mass (FFM). Comparisons with theoretical calculations of BMR were also made. The athletes were shown to have a significantly higher BMR than was expected from calculations based on body mass (16%, P < 0.05) or body composition (12%, P < 0.05). There were no corresponding differences found in the nonathletic control group. The athletes had a 13% higher (P < 0.001) BMR than controls if related to FFM and 16% (P = 0.001) if related to both FFM and fat mass (FM). The athletes were also 10% lower R-values (P < 0.01), indicating higher fat oxidation. The conformity of these findings with the present literature and the possible mechanisms behind them and their influence on theoretical calculations of energy turnover (ET) based on activity factors expressed as multiples of RMR are further discussed.

Many contemporary world-class ski jumpers are alarmingly underweight, and several cases of anorexia nervosa have come to light. Athletes strive for low body weight because it gives them a major competitive advantage. To stop this hazardous development, changes to the regulations are being discussed. The International Ski Federation and the International Olympic Committee wish to be proactive in safeguarding the interest of the athletes and their health.

This study of ski jumping uses field studies conducted during World Cup competitions. Large-scale wind tunnel measurements with 1:1 models of ski jumpers in current equipment and highly accurate computer simulations of the flight phase that include the effects of the athlete’s position changes.

Health First

Particular attention has been directed to designing a reference jump that mirrors current flight style and equipment regulations (2001) and investigating effects associated with variation in body mass in skiing, air density, and wind gusts during the simulated flight. The detailed analysis of the physics of ski jumping described in this article can be used to investigate all initial values and parameter variations that determine the flight path of a ski jumper. It will form a reliable basis for setting regulations that will make it less attractive or even disadvantageous for the athlete to be extremely light.